Integrated circuits and integrated-circuit technologies, including the complementary-metal-oxide-semiconductor integrated-circuit-fabrication technology (“CMOS”), represent the backbone of modern electronics. Integrated-circuit microprocessors are the computing engines for modern computer systems, which use integrated-circuit electronic memories for storing data processed and produced by microprocessors. Special-purpose integrated circuits are employed as controllers in a wide variety of consumer products, from appliances and automobiles to cell phones, cameras, and children's toys.
Relentless increases in the densities of circuitry and decreases in the sizes of signal lines and other circuit elements fabricated within integrated circuits are largely driven by the need to produce ever faster and more capable microprocessors for computer systems. In general, improvements in microprocessor integrated circuits and technologies for designing and manufacturing microprocessor integrated circuits are quickly assimilated into the design and manufacture of the various types of integrated circuits used in all of the other types of devices and systems that employ integrated circuits, providing a large market eager for each new generation of integrated-circuit technology.
The photolithography-based methods currently employed to manufacture integrated circuits are associated with certain physical constraints that may limit the degree to which traditional integrated-circuit technology can continue to be improved. As the dimensions of signal lines, transistors, and other electronic components of submicroscale circuitry further decrease, the reliability with which such components can be manufactured and with conventional photolithography-based methods is also decreasing, resulting in decreasing yields of functional integrated circuits during manufacturing and problems associated with the operational characteristics of integrated circuits. Below certain dimensions, the behavior of electrons and electron-currents is increasingly governed by quantum mechanics, and uncertainties in electron position and momentum translate into difficulties in designing and fabricating tiny electronic components that operate in compliance with desired models and behaviors developed for larger-scale components. For this reason, new nanoscale technologies, including nanowire-crossbar arrays, have been developed in order to push densities of memory-storage elements to much greater levels than can be achieved by current photolithography-based fabrication techniques. Nanowire crossbars can be fabricated using nanoscale imprint lithography, molecular self-assembly, and other techniques that are not constrained by diffraction limits of electromagnetic radiation, which constrain photolithography. Designers, manufacturers, and, ultimately, users of electronic devices and systems based on integrated circuits and integrated-circuit memories continue to seek further improvements in processor speeds and memory densities using these newer technologies, including nanowire-crossbar arrays, combined with traditional photolithography-based integrated circuits.